Roof coatings are appropriate for aging low-slope or metal roofs that are: 1) dry and, 2) still capable of keeping water out.
A coating applies a new outer surface over the existing roof, similar to adding a protective layer of paint that cures over the surface. The two most common compositions are silicone and acrylic.
Unlike a layoverInstallation – A layover (recover or overlay) is a method of installing a new roof membrane over an existing roof system without removing the existing roof. More, which installs a new roof membraneMaterial - A single-ply membrane is a roof covering that uses one continuous layer of material to waterproof low-slope roofs. More over the existing roof, or a replacement, which removes the existing roof systemRoof Types - A roof system (roof assembly) is the entire series of roofing layers and components above the roof deck that work together to weatherproof the building. More altogether, a coating relies on the roof beneath it to remain functional.
Although coatings may serve several purposes, like UV resistance or slowing general wear, coatings are only as effective as the roof system below it. If moisture is already trapped in the roof system, a coating will seal that moisture inside.